I don't blame you for your hatred of Silva....but I'm going to get a little nit-picky w/ parts of your original post farmer:
1. He's properly rated - the entire league knows he sucks.
2. "Never got more than 5, maybe 6 innings". Really?! Did you happen to look at his stats before throwing those numbers out there? If you're going to kill the guy, at least be a little bit accurate. Here are his starts:
4/9/10 - 6 IP (ND)
4/16/10 - 7 IP (W)
4/21/10 - 6 IP (W)
4/26/10 - 7 IP (ND)
5/1/10 - 5 IP (ND)
5/7/10 - 5 IP (W)
5/12/10 - 6.1 IP (W)
5/18/10 - 6 IP (W)
5/23/10 - 5.1 IP (W)
5/29/10 - 7 IP (W)
6/7/10 - 7 IP (W)
6/12/10 - 7 IP (L)
6/18/10 - 6 IP (L)
6/26/10 - 6 IP (ND)
7/1/10 - 7.2 IP (ND)
7/6/10 - 6 IP (W)
7/11/10 - 1.1 IP (L)
7/19/10 - 1 IP (L)
7/26/10 - 5 IP (W)
8/1/10 - .1 IP (L)
9/7/10 - 5 IP (L)
In looking at that, I see a lot of quality starts. the losses and no decision before the all star break were by 1 or 2 runs, so it's not like he was getting shelled. He's a contact pitcher, not going to strike a ton of guys out, and will rely on his defense to make plays and get guys out. The Cubs D wasn't exactly great last year either.
3) Russell is not a starter. Plain and simple. He couldn't start effectively in the minors and there is little to no reason to believe he can be the lefty starter in the majors. Cashner deserves a shot as long as he continues developing his secondary stuff and not rely on the fastball so much.
Just my two cents anyway. I'm not a Silva fan by any means, but you made it sound like he was much more terrible than what he actually was.